Laser scan-based point clouds can be enormously valuable in the process of efficiently authoring an as-built Building Information Model (BIM). Much of the value Point Clouds bring depends on efficiently using them to assist in your model authoring process, and this article will outline the best practices for efficiently working with multiple scan files in a Revit project.
Point Clouds of a building typically consist of many Laser Scans. While it is possible to index and subsequently link each individual scan into your Revit project, it is much more efficient to aggregate the scans into logical regions of your building, and use those aggregations in your Revit project. Instead of having 10s if not 100s of different scans, you can have only a few Point Cloud files to work with in the project. This provides a much more efficient process within Revit, making it significantly easier to manage the scan visibility and deliver optimal performance.
Throughout this best practices article, the following key principles will help you be successful:
Most commonly, a point cloud consists of multiple laser scans that are taken in different locations of the building, and positioned relative to each other through a process called "registration". Registration is completed by finding common points between different laser scans, and using those common points to calculate the exact location and orientation for each scan.
Point Clouds typically consists of huge amounts of data. In order to rapidly access that data within Revit, a process called Indexing must be carried out to optimize the data structure for rapid access. This process is called indexing.
The following practices are recommended for optimal efficiency working with large laser scans within a Revit project:
- Aggregate Scans within Scanner Software
Once Registration is complete within the scanner software, you typically can group scans into Clusters. It is a best practice to group those scans based upon logical regions in your building, which will likely align with the Views you have created within your Revit project. For example, you can have a group for exterior scans, a group for each floor, or sections of each floor. Once grouped, you can export the group to an individual point cloud file.
- Index and Link the Aggregated Files
With individual files for each aggregated scan, you can now go through the indexing process to organize the data into the PCG file format for Revit's point cloud engine. Once indexed, be sure to link in each PCG file using the "Auto - Origin to Last Placed" option in the "Link Point Cloud" dialog, as seen below.
- Toggle the Visibility of Aggregated Scans
Once linked into your Revit project, you can now easily control visibility of Scans within the Visibility/Graphics menu for Views. Note that you do not need to hide scans that do not show up in the View Range of your Project View, Revit does not access them.